Inflatable packer formation tester



Nov. 8, 1960 R. H. BLOOD INFLATABLE PACKER FORMATION TESTER 4 Sheets-Sheet 1 Filed 001;. 26, 1956 FIG-I Robert H. Blood Inventor By y m Attorney 4 Sheets-Sheet 2 Inventor Nov. 8, 1960 R. H. BLOOD INFLATABLE PACKER FORMATION TESTER Filed Oct. 26, 1956 F I'Gr 2 Robert H. Blood 8)! M 4? Attorney Nov. 8, 1960 R. H. BLOOD INFLATABLE PACKER FORMATION. TESTER 4 Sheets-Sheet 5 Filed Oct. 26, 1956 Robert H. Blood Inventor By wd. Attorney Nov. 8, 1960 R. H. BLOOD 2,959,226

INFLATABLE PACKER FORMATION TESTER- Filed Oct. 26, 1956 4 Sheets-Sheet 4 FIG-4 Robert H. Blood Inventor United States Patent 2,959,226 7 a a INFLATABLE P ACKER FORMATION TESTER Robert H. Blood, Tulsa, Okla., assignor, by"nie sne assignments, to Jersey Production Research Company Filed on. 26, 1956, Ser. No.'61s,s19 3 Claims. (or. 166-187) This invention concerns improved apparatusfor testing subterranean formations. More particularly, the invention relates to well testing apparatus which utilizes an inflatable packer and a retrievable chamber containing gas for driving a fluid into the packer and thereby inflating the packer. The apparatus of the inventionis especially characterized by the fact that it is attachable to the lower end of a string of empty well pipe and that fluid from a particular subterranean formation may flow from the formation up through the well pipe. The ap- 'parat'us of the invention is further characterized by comprising an up hole formation tester which may be set and reset at more than one level withina well or borehole without withdrawal of the tester from the hole.

It is a frequent and well known practice in drilling oil and gas wells totest subterranean'formations for the types of fluid contained therein ,and also for the production characteristics of the formations. The nsual procedure for testing a formation consists in using packers to isolate the formation and thereafter withdrawing fluid from the formation for testing purposes. Thus, the usual technique for testing a formation near the bottom of a hole is to run a string ofpipe into the hole witha packer attachedpto the lower end 0f the formation through the tubing or well pipe upon which the packers are mounted. Generally speaking, paclrers of this type-Le. sleeve packersrequire the use of tail pipe or other complex devices for positioning and setting the packers. Furthermore, heavy loadings are usually required on the well pipe and tail pipe in order to cause the packers to formfand maintain effective seals.-

In view of the difliculties in using sleeve type straddle packers it has recently been suggested that'inflatable packers be used in connection with up hole formation testing. An especially eifectiv'e tester of this type has been described and claimed in US. Patent No 2,600,173 of B. W. Sewel1 and G. H. Ramsey, issued June 10, 1952. This particular tester is supported on the lower end of a pipe string and utilizes an inflatable packer which is provided with one or more fluid passageways in its wall portions. The packer is positioned directly opposite a formation to be tested and is thereafter inflated so as to form a seal against the wallof the bore hole or. well at this point. The wall passageways in the packer enable fluids to flow from the formation into a sample chamber which is employed in conjunction with the tester. The pressures necessary to inflate the packer in this testerare obtained by pumping drilling mud or. other suitable fluid 2,600,173 mentioned earlier.

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2 a down within the well pipe and thence into the packer. Release of the packer following a testing operation -is realized by merely releasing the hydraulic pressure existing within thepacker. 1 a

While the formation tester just described possesses a number ofdesirable features, and while it has proven to be quite satisfactory in testing up-hole formations, it should be noted that it requires; the presence of drilling mud or other fluids within the well' pipe to'which itis attached in order to inflate the packer element. In some instances this is a disadvantage, e.'g. where it is desirable to obtain production from the formation directly within the well"pipe.

Accordingly, it is an-object-of this invention to provide an improved type of formation tester wherein formation fluids may escape from -a formation and flow directly through a-wel-l-pipe. It is a further object of the 'invention'to provide an up hole formation tester which may be operated on empty well pipe or tubing, and which may beset and reset repeatedly within a well or bore hole without requiring withdrawal of the apparatus from the hole. I I

These and related objectives, which will be explicitly considered or readily apparent in the following description and in the attached drawing, are realized by means of 'a testingapparatus assembly which includes an inflatable packer of the type described in US. Patent The apparatus assembly further includes achamber normally filled with a fluid which is used to inflate thepacker. A gas-filled retrievable chamber is adapted to be attachedto the testing assembly soas to release gas and thereby drive thefluid from the above-mentioned chamber into the packer. Suitable passageways, check valves and the like are alsoprovided in theassembly as will he discussed hereinafter to enable the various fluids to flow in the desired manner and at thedesired times.

The invention may be better understood by reference to the' attached drawing which illustrates a preferredcmbodiment of the invention and which depicts the best mod contemplated for carrying out the invention. a .s .i

Figure 1 illustrates in partial cross-section view. an upperportion of an apparatus assembly which constitutes a preferred embodiment of the invention.

Figure-2 is a cross-section view particularly illustrating an inflatable, packer of atypesdescribedinUS. 2,600,173, mentioned above. The apparatus depicted in ,this, figure constitutes the lower portionfofzthe apparatus whichis illustrated in Figure l, and it will be noted that the packer inrhisfigure .is shown in. an inflated condition,

Figure. 3 is a cross-section view vshowing in detail-a retrievable gas container in a locked position within the tester assembly and in a condition to exert gas pressure on the fluid which is employed to inflate the packer.

Figure 4 is a cross-section view of the gas container of Figures land 3 in a condition suitablefor loweringor raising withina string of well pipe to which the tester assembly is attached. :1-

Figure 5, is a section view taken along the section lines VV of Figure 4. 1 Referring first to Figures 1 and 2, it will be seen that the apparatus illustrated in these figures includes a tester body member 10, fluid chamber 11, packer-12, gas container 13, container receiver20, piston 14, valve stem 15, and check valves, 16, 17 and 18.

Body member 10 is threaded at its upper end so astobe attachable to the lower end of a pipe string and is essentially anelongated cylindrical member divided in.three main,,sections. The lowermost section; is in. effect,;-a mandrel 19 which together with sleeve 21 generally'constitutes packer 12. Positioned above. the mandrel/19 :is the fluid chamber 11 which constitutes an intermediate a bore hole.

controls the operation of the overall tester.

section of the body member 10. Interposed between mandrel 19 and chamber 11 are check valves 16-18 inclusive and fluid passageways which interconnect these two sections of the tester. -,,Immediately above the fluid chamber 11 is the uppermost section 20 of the tester which is adapted to receive gas container 13, and which is further adapted to be attached to a pipe string not shown.

Referring now specifically to the packer 12, it will be observed that this element of the illustrated apparatus includes mandrel 19, inflatable sleeve 21 and upper and lower clamping rings 22 and 23 respectively. The clamping rings serve to secure and seal the upper and lower ends of the sleeve 21 to the mandrel 19. It will be noted that the upper and lower ends of the mandrel are preferably enlarged somewhat as illustrated at the points of contact with the sleeve.

' The construction and nature of the inflatable sleeve 21 has been considered at length in the afore-mentioned Sewell and Ramsey patent, and it is not considered neces- 'fabric embedded therein for reinforcement purposes.

Fluid passageways are provided in the sleeve 21 to enable fluid to pass from a formation surrounding the sleeve to a point within or above the sleeve. Thus, as illustrated in Figure 2, one or more recesses or pockets 24 areformed in the exterior surface of the sleeve and are preferably filled with bead chain or other suitable interconnecting packing elements to prevent the pockets from collapsing when the sleeve is expanded against the wall of The bead chain or other packing elements may be maintained in position within the pockets 24 by means of wires, clamps or other suitable devices. be noted that the bead chain or packing elements in addition to supporting the pockets 24 also provide a porous structure through which fluids may readily pass.

Extending upwardly from the pockets 24 are flexible conduits 25 which interconnect pockets 24 with fluid passageways 26. Conduits 25 may be fabricated from flexible wire hose, rubber hose, or the like. They must be collapse-resistant, fluid-impermeable and flexible in character. It should be pointed out at this point that the It will be noted, however, that the sleeve It will packer in Figure 2 is in an inflated condition; and that in a deflated or normal condition, the sleeve 21 is essentially of the same outside diameter as the portion of the sleeve locked between the mandrel and the clamping rings 22 and 23.

As mentioned earlier, sleeve 21 is inflated by means of a liquid which is normally contained within fluid chamber 11. Chamber 11 includes piston 14, valve stem 15 and associated check valves and fluid passageways that connect it to the packer 12. At this point it will be noted that the fluid within chamber 11 need not be any special or particular form of fluid, except that it be suitable for the application stated above. For example, the fluid may be drilling mud, mineral oil, water, or any other synthetic or naturally-occurring fluid which is suitable for use in setting an inflatable packer of the type described. The nature and structure of valve stem 15 is important in the illustrated apparatus, since it is this member which In other words, the position of the valve stem determines when the packer may be inflated; and it also determines when the packer may be deflated and raised or lowered within a well.

Valve stem 15 is provided with a central longitudinally disposed fluid passageway 38 which extends in effect from an upper port 31 to a lower port 32. Upper port 31 is ports 31 and 32. An enlarged shoulder 33 is provided on the outer surface of the valve stem and is adapted to cooperate with spring 34 so as to maintain valve 18 normally closed. As indicated in the Figure 1, check valve 18 is positioned at the lower end of the valve stem. More particularly, valve 18 is an upward facing valve adapted to regulate the flow of fluid between fluid chamber 11 and sleeve 21. The conduit through which the fluid passes in traveling from chamber 11 to sleeve 21 is designated by the legend 35 in the drawing.

The positions of the ports 31 and 39 bear an important relationship to the functioning of the apparatus of this invention. Thus, ports 31 must be located such that passageway 30 is not vented to the drill stern except when it is desired to remove the entire apparatus from a well bore. Similarly, port 39 must not vent drilling mud from the bore hole through the packer pockets and into the chamber 11 below the piston 14, until enough fluid has passed from the bag 21 to deflate the packer sufliciently to permit its ready movement within a bore hole. These features and functions will become more apparent later in this description.

Disposed about valve stem 15 and positioned within fluid chamber 11 is piston 14. This memberi.e. piston 14is in effect a free floating type piston and is of a character to slide along the outer surface of the valve stem and also along the inner wall surface of the chamber 11. Fluid seals 36 are provided as desired or necessary between the piston and the valve stem or the wall of the fluid chamber in order to effect a fluid-tight relationship therebetween.

As mentioned above, fluid conduit 35 leads from the bottom end of fluid chamber 11 into the sleeve 21 via the check valve 18. A second conduit, identified by the legend 37 in the drawing, similarly extends from the lower end of the fluid chamber 11 through a check valve 16 into the annular space between the overall tool or tester and the wall of the surrounding well or bore hole. Check valve 16 is arranged in the apparatus so as to resist the flow of fluid from the chamber into the well or bore hole until the packer is entirely inflated and set. It is further adapted to block the flow of any fluid in the opposite direction, i.e. from the well or bore hole back into chamber 11.

A third conduit 38 is provided to establish direct fluid communication between passageway 30 in valve stem 15 and the passageways 26. Production check valve 17 is provided in conduit 38 and is adapted to block the flow of fluid from passageway 30 down toward the pockets 24. This check valve, it will be noted, is provided with a spring or other resilient means to permit the flow of fluids from the pockets and thence into the passageway 30.

Section 20 of the tester is provided above fluid chamber 11 and may be generally described as a special sub for connecting the tester to the bottom of a string of well pipe. It is also adapted to receive gas container 13 as Well as tools adapted to depress valve stem 15, when the apparatus is to be moved within a bore hole or removed entirely from the hole.

To enable section 20 to be attached to the lower end of a string of well pipe, this section is provided with suitable threads 40 or other means normally employed for effecting such an attachment. It is also provided with a restricted passageway 41 at its lower end which leads to the intermediate or fluid chamber section 11. The shoulder 42 between restricted passageway 41 and the enlarged interior portion 43 of section 20 is adapted to cooperate with gas container 13 as well as with tools employed to depress valve stem 15..

In order that gas container 13 may be locked within section 20 as gas escapes from the container and flows into chamber 11, suitable retractable 'interengaging means are providedbetween container 13 and section 20. The inter'engaging means illustrated in the drawing includes a peripheral recess 44 in the inner wall surface of section on the container.

passageway 41. be made more apparent later in this description. Passageway 41 is continuously connected to the portion'df 20 and expandable dogs or latches 45 which are mounted The recess 44 is provided with a downward facing shoulder 46 which cooperates with the dogs 45 to restrain container 13 from moving upwardly when gas is released from the container.

It should be noted at this point that the upper end of valve stem 15 normally protrudes from the upper end of chamber 11 and extends into the lower-end of restricted The reason for this arrangement .will

ingly, attention is directed primarily now toward Figures 3-5 inclusive in which a suitable gas container is shown "in section form.

As may be seen in Figures 1 and 3-5 gas container 13 comprises an outer body member 50 and an inner mandrel-like member "60. The outer member 50 includes an upper gas chamber 51 and a lower elongated passageway 52. A port 57 connects passageway 52 with the pipe in which the gas container is positioned; and an intermediate slot or port 58 connects the passageway with gas chamber 51. Below port 58 and spaced therefrom are two radially opposite slots or ports 53. The upper end of each of these ports is defined by a downward and outward facing surface 56; and the lower end of each such port terminates in an elongated recess 55. The upper end of the wall surface of each recess 55 terminates in an upward and inward facing surface 59. The lower end of the gas container may be a flat shoulder or surface 54 as illustrated.

The mandrel-like portion 60 of gas container 13 is essentially an elongated cylindrical member which has a piston 61 at its upper end, a section 62 of reduced diameter immediately below the piston, and a section 63 of enlarged diameter spaced slightly above its lower end.

The central length or portion of mandrel 60 i.e. the portion between reduced section 62 and enlarged section 6 3is of a diameter adapted to slide vertically within passageway 52 in a fluid-tight relation. Piston rings 64 "and/or seal rings 65 or equivalent means may be employed as desired for insuring a fluid-tight relationship. The enlarged section 63 has an upper square shoulder '66 which is adapted to engage the lower end 54 of the outer body member 50. The lower surface 67 of section 63 tapered upwardly and adapted to engage matching shoulder 42 described earlier herein. A cup seal 68 or equivalent packing means is positioned immediately below section 63 and may be held in position as by means of nut 69 or any equivalent device. Cup seal 68 is adapted to form a fluid tight seal with the wall surface of passageway 41 when lowered therein.

A central passageway 70 extends from the lower end of mandrel 60 to a point spaced somewhat below reduced section 62; The upper termination of the passageway is such that it is directly opposite slot 58 of body member 50, when shoulder 54 engages shoulder 66; Thus, there is at this point a direct fluid passagewayfrom ga's chamber 51 through the central passageway 70 and thence to a point below thegas container.

A pair of radially opposite dogs or latches 71 are mountedlon mandrel 60 at a point intermediate shoulder 66 and the upper end of passageway 70. The dogs are of a size so as to fit within the recesses 55, and they are adapted to move laterally outward from mandrel 60 byvirtue of pivots 72. The upper end of each dog is preferably provided with a tapered surface or chamfer 73 which is adapted to engage the upper surface 56 of slot5 3. When expanded outward, the dogs or latches are further adapted to engage the peripheral recess or groove 44 in section 20. When expanded in this manner the upper end of each dog is further adapted to engage the peripheral shoulder 46 in a locking arrangement.

A spearhead or equivalent device is provided at the upper end of gas container 13 to receive a wire line or other suitable means for raising or'lowering the gas container within a hole.

As mentioned earlier, section 20 is also intended to receive tools adapted to depress valve stem 15. Such tools may simply be weighted members of the same general shape as the gas container 13. Furthermore, they may be provided with expandable dog mechanisms similar to those used in the gas container assembly. The tools must be adapted to rest on shoulder 42 and extend downward from the shoulder 42 to engage the upper end of the valve stem 15. One tool, to be used when the tester is to be merely moved from one location to another in a well bore, must'be of a character to open check valve 18 without exposing 'ports 31 to chamber 11. Another tool, to be used when the tester is to be removed entirely from a hole, must be of a character to not only open valve 18 but also open ports 31 to chamber 11. The tools preferably are provided with spearheads or the like for wire line operation.

Having thus outlined the structural components of the apparatus depicted in the drawing, a more complete understanding of the invehtion may now be had by briefly considering the manner in which these components function with respect to one another. In this connection it will be assumed that the apparatus is attached to the lower end of a string of well pipe-Le. drill pipe, casing tubing or the like-which is positioned within a bore hole 90. It will further be assumed that it is desired to obtain a sample of fluids that may be contained within a formation 91 penetrated by the hole 90. It will also be assumed that bore hole is filled with a head of drilling mud or equivalent liquid sufficient to at least counterbalance the pressures of fluids within formations pierced by the hole.

As noted earlier in this description, Figures 1 and 2 of the drawing depict the apparatus illustrated therein as it exists when the packer 12 is inflated and in actual contact with a subterranean formation. None of the figures show the tester body and the packer in the cond.tion required for raising or lowering it within a well or bore hole. Such a condition, however, will be readily apparent to persons skilled in the art.

Referring to Figures 1 and 2, the following differences in the condition of the illustrated apparatus exist when the apparatus is retracted and suitable for movement within a well or bore hole. First, the piston 14 is positioned at the top of fluid chamber 11, and fluid chamber 11 is completely filled below piston 14 with a fluid suitable for inflating packer 12. Second, inflation check valve 18 is closed, and sleeve element 21 of packer 12 is contracted so that its outer diameter is substantially equal to the outer diameter of tester body 10. It will be recognized at this point that chamber 11 below piston 14, passageway 35 and sleeve 21 are also preferably filled with a suitable fluid at this time. It will also be recognized that spring 34, resting against the wall of passageway 37, must exert suflicient force against the underside of shoulder 33 to maintain check valve 18 in a normally seated condition.

With tester body 10 attached to the lower end of a string of pipe, and with packer 12 in a deflated condition, the tester assembly of Figures 1 and 2--exclusive of gas container 13is lowered within bore hole 90 until the pockets 24 of the packer 12 are directly opposite formation 91. At this point gas container 13 is lowered through the empty drill pipe until it enters upper section 20 of the tester assembly.

It will be recognized that the gas container 13 is in the condition illustrated in Figure 4 as it travels down the pipe and initially enters section 20.

Specifically, body member 50 is in its vertically uppermost position relative to mandrel 60, and the dogs 71 are fully retracted within recesses 55. Piston 64 is positioned within passageway 52 above port 58, and the upper termination of passageway 70 is laterally opposite one of ports 53.

A shear pin 92 is preferably used to provide a mechanical interlock between the body member 50 and mandrel as.

Furthermore, a gasiform material is stored within gas Y chamber 51 under a pressure and in a volume sufficient to satisfactorily displace the liquid from chamber 11 so as to inflate sleeve 21 and seal the inflated sleeve against the wall of the bore hole 90 when desired. Suitable gases for the purpose will be readily apparent to persons skilled in the art and may include nitrogen, air, methane, the chemically inert gases, and the like.

As gas container 13 passes downwardly within section 20, the following events occur. First, the cup seal 68 enters passageway 41 and effects a fluid-tight seal along the inner periphery of the passageway. Shoulder 67 then engages and abuts against shoulder 42 with the result that the weight of the gas container 13 is now transferred from the Wire line or other device supporting the gas container to the shear pin 92. Resulting fracture of the shear pin causes body member 50 to move downwardly relative to mandrel 60.

As body member 50 moves downwardly, recesses 55 also move downward relative to the dogs 73, and the dogs are then free to move outward around pivots 72.

At this point it will be noted that outward movement of the dogs may be realized by means of suitable spring elements; but the use of such elements is not critically necessary, since shoulders 56 also may serve the same purpose. Thus, the lower ends of shoulders 56 may be adapted to engage the chamfer surfaces 73 after the dogs 71 are disengaged from recesses 55. In any event, as the dogs move outward from mandrel 60 they expand into the peripheral recess 44. It will be recognized, of course, that the position of the peripheral recess 44 relative to the shoulder 42 must be suitable for the dogs to expand therein in proper time sequence relative to the entry of seal 68 Within passageway 41 and engagement of shoulder 67 with shoulder 42.

Piston 61 moves upwardly within passageway 52 simultaneously with the movement of the dogs 71 from the recesses 55. Any gas or fluids trapped above the piston are vented through port 57 directly into section 2.0 and thence the attached well pipe. Simultaneously, the body 50 moves downward relative to mandrel 60 until the passageway 70 is aligned with slot 58. It will be apparent that alignment of passageway 70 with port 58 must not take place before dogs 71 have actually entered into the recess 44. It is preferred that there be a slight time delay between the expansion of the dogs and the alignment of the passageway 70 and the port 58.

At this point in the operation of the illustrated equipment, the gas container 13 is in the condition illustrated in Figure 3. There it will be seen that gas is now free to flow directly from chamber 51 through port 53 and thence through passageway 70 into fluid chamber 11 immediately above piston 14. The piston moves downward within chamber 11, and fluid is diplaced from the chamber through check valve 18 into sleeve 21. As a result of this action, sleeve 21 is completely inflated and sealed against the bore hole wall and pockets 24 are thrust directly against formation 91.

Piston 14 is driven completely to the bottom of chamber 11 in response to the pressure exerted by the aforementioned gas from container 13. Any liquid over and above the amount required to inflate and seal packer 12 is Having inflated and seated the packer 12, and having emptied chamber 11 of its liquid content, gas container- 13 is removed from section 2%) by pulling upward on spearhead 80. It will be recognized that upward movement of the spearhead and the gas chamber causes the body member 50 and the mandrel '60 to return from the condition of Figure 3 to the condition of Figure 4. Release of the cup seal 68 from its position within passageway 41 is facilitated by virtue of the pressure equalization which occurs when the upper end of the passageway 70 is once against aligned with slot 53. Fluid is now free to flow from formation 91 through pockets 24 and thence through conduits 25, passageways 26, check valve 17, passageway 38, port 32, passageway 30, ports 39, passageway 47, passageway 41 and section 20 into the' well pipe. Production of the fluid in this manner may be maintained as long as desired.

When it is desired to cease sampling formation 91, the tester may be retrieved from the well bore by merely dropping one of the aforesaid tools through the string of pipe until it enters section 20 and urges valve stem 15 downward thus opening check valve 18 and exposing ports 31 to chamber 11. Fluid within sleeve 21 is immediately free to flow into chamber 11 thus deflating packer 12 and also raising piston 14 within chamber 11.

When packer 12 is deflated, it will be apparent that fluid within the bore hole is free to enter pockets 24 behind the formation fluid that previously entered the pockets. Entry of the bore hole fluid through the pockets and eventually into the well pipe may continue so long as a sufficient differential exists between the pressure in the bore hole and the pressure within the well pipe. By maintaining the bore hole full of drilling mud or other liquid which is heavier than the formation fluid, it will be recognized that migration of the bore hole fluid into the well pipe may continue until substantially all of the formation fluid is displaced from the well pipe. It may be necessary, of course, to periodically or continuously add drilling mud to the bore hole during this part of the operation. It will further be apparent that this migration of the bore hole fluid into the well pipe is distinctly, advantageous, since it is much preferred in the art to pull or withdraw a string of pipe filled with drilling mud rather than one filled with hydrocarbons or other formation fluids. Furthermore, the formation fluid may be continuously withdrawn from the well pipe at the surface of the earth before the tester is retrieved from the sampling position. Thus, this type of apparatus insures not only complete control of a sampling operation; but it also minimizes unsafe operating conditions.

Following the termination of a sampling operation at a formation such as is identified by the legend 91 in the drawing, the apparatus may be entirely withdrawn from the bore hole; or alternatively, it may be repositioned opposite a second formation and a new sample obtained. The latter type of procedure may be attained by simply dropping a tool through the pipe string which depresses valve stem 15 sufficiently to open valve 18 without exposing ports 31 to chamber 11. In this instance fluid escapes from sleeve 21 into chamber 11, thus deflating packer 12 and raising piston 14. When the pockets 24 are clear of the formation, drilling mud enters the pockets and flows through passageways 25, 26, 38 and 30 and ports 32 and 39 into chamber 11. Some of the mud may actually enter chamber 11 above piston 14, but as soon as the liquid escaping from sleeve 21 raises piston 14 above ports 39, the mud entering from the pockets then merely helps to return the piston to the top of chamber 11. The tester is then in condition for movement to a new test position.

At this point it will be noted that the foregoing descrip tion and the attached drawing are intended to present a preferred embodiment of the invention, and there is no intention to limit the scope of the invention to this particular embodiment. It is contemplated that numerous variations and modifications may be made to the described embodiment without departing from the spirit ofvthe invention. For example, it will be apparent that several techniques may be employed for preventing the formation of excessive pressures on the sleeve element of the packer during its inflation. Thus, inflation check valve '18 may conveniently be a difierential area valve'adapted to close when the pressure within the packer reaches a predetermined value. Alternatively, a relief valve 'po'sitioned above piston 14 through a suitable pressure indicator disposed in the passageway 35 can be adapted to vent or otherwise dispose of the gas from container 13, when the pressure in the packer becomes excessive.

It will be recognized, of course, that the use of a variable area valve or a gas relief valve, such as has just been described, may eliminate the necessity for the bypass check valve 16. Furthermore, the ports 39 and 31 may then be replaced by ports that are sealed by piston 14 when the piston is in its uppermost position within chamber 11. It would be necessary, of course, that such ports be adapted to bypass the piston when check valve 18 is opened preparatory to removing the tester completely from a well or bore hole. The nature of such modifications will be readily apparent to persons skilled in the art; and a detailed dissertation on the nature of such modifications is not considered to be necessary for an adequate understanding of these aspects of the invention.

It will also be recognized that an orifice or other flow restriction device may be placed in the exit connection from the gas container 13 in order to gradually release the gas from within the container upon inflating the packer. It is conceivable that gradual release of the gas would be desirable in some instances in order to avoid sudden pressure surges within the tester.

To summarize briefly, the present invention concerns a formation tester which is attachable to the lower end of an empty pipe string and which utilizes an inflatable packer having exterior mounted fluid-receiving pockets or recesses. A cylinder adapted to be filled with liquid is mounted above the packer and is fitted with a piston adapted to drive liquid from the cylinder into the packer. A retrievable gas-filled container, lowerable through the pipe string, is adapted to release gas into the chamber and to drive the piston downward therein. Means such as relief valve, differential area valve or the like prevents the packer from experiencing an excessive inflation pressure; and releasable check valve means prevents premature loss of pressure from the packer, once it is inflated.

Conduits mounted exterior of the packer conduct fluid received by the pockets into the pipe string through a passageway provided with a check valve and ports operable (1) to block the passageway at times prior to inflating the packer, and (2) to clear the passageway when the packer is inflated. Means are also provided for clearing the passageway and the packer check valve when desirede.g. when deflating the packer and removing the tester from a bore hole. In a preferred version of the tester, ports disposed in the passageway are additionally adapted to transmit liquid received from the pockets into the cylinder during deflation of the packer so as to insure that the cylinder is full of liquid prior to a subsequent inflation.

What is claimed is:

I. An apparatus for testing a subterranean formation from a well bore penetrating a formation which comprises: a tubular sub attachable at its upper end to the lower end of a string of pipe disposed within the well bore, a cylinder having closures at each end and adapted to hold a liquid, said cylinder attached at its upper end to the lower end of said tubular sub and adapted to contain a liquid, a first fluid passageway interconnecting said sub with said cylinder, an inflatable packer attached to the lower end of said cylinder, a second fluid passageway interconnecting said cylinder and the interior of said packer, a first check valve within said second passage- 1 10 way to enable fluid to flow selectively from said cylinder iiit'o 'saidpaekerfa threeosition valveste'mbnsaft' first check valve extending through said cylinderandt'eiiii inating within said sub, said stern penetrating the upper and lower closures of said cylinder in a slidable fluidtight relation,'a piston fitted within said cylinder in a "slidable, fluid-tight relation with said valve stem, a-fluidreceiving pocket recessed in the exterior surface of said packer, a conduit leading from said pocket to the closure between said packer and said cylinder, a second check valve in said conduit enabling fluid to flow selectively from said pocket, a third fluid passageway extending longitudinally within said valve stem, said valve stem having an upper port, an intermediate port, and a lower port extending through the wall thereof to said third passageway, said intermediate port terminating within said cylinder at a point below said piston when the piston is at the upper end of its stroke within the cylinder, and above said piston at the lower end of the stroke of the piston, said valve stem in an uppermost position having said first check valve and said upper port closed and said lower port in fluid communication with said conduit, said stem in an intermediate position having said first check valve open, said upper port closed, and said lower port in fluid communication with said conduit, said stem in its lowermost position having said first check valve open, said lower port in communication with said conduit, and said upper port in communication with the upper end of said cylinder, said stem being actuatable from said pipe string through said cylindrical section to take said positions.

2. An apparatus for testing a subterranean formation from a well bore penetrating the formation which comprises: a tubular sub attachable at its upper end and in fluid communication with the lower end of a string of well pipe suspended within the well bore, a cylinder closed at each end and adapted to hold a fluid, said cylinder attached at its upper end to the lower end of said sub, an inflatable packer attached to the lower end of said cylinder, a first fluid passageway providing fluid communication through the closure between said sub and said cylinder, a second fluid passageway providing fluid communication through the closure between said cylinder and said packer, a first check valve within said second passageway to enable fluid to flow selectively from said cylinder to said packer, a three-position valve stem having a central fluid passageway, said stem attached at its lower end to said first check valve and extending upward through said cylinder in aslidable fluid-tight relation with the closures at the ends thereof and terminating within said sub, said stem having a first wall port near its upper end, an intermediate wall port leading within said cylinder and a lower wall port near its lower end, a piston fitted within said cylinder and adapted to slide along said valve stem to each side of said intermediate port, a fluid-receiving pocket recessed within the exterior wall surface of said packer, a conduit leading from said pocket and terminating at its upper end in the closure between said packer and said cylinder, said valve stem biased normally to an uppermost position wherein said first check valve and upper ports are closed and said upper port is in communication with said conduit, said valve stem in its lowermost position having said first check valve open, said lower port in communication with said conduit and said upper port in communication with the upper end of said cylinder, said valve stem in an intermediate position having said first check valve open and said lower port in communication with said conduit, said valve stem being operable from within said pipe string through said cylindrical section to take said intermediate and said lowermost positions.

3. An apparatus as defined in claim 2 including a pressure relief valve adapted to vent fluid from the lower er d,

'ofsaid cylinder when the pressure therein exbeeds a preselected value. 1

References Cited in the file of this patent UNITED STATES PATENTS West Oct Sewell Dec. Williams Apr. Baker et a1. Nov Williams Nov 

